


Survival of the Fittest

by Soulstes



Category: Undertale (Video Game)
Genre: Adult Frisk (Undertale), Alpha/Beta/Omega Dynamics, Alternate Universe - Underfell (Undertale), Attempt at Humor, Attempted Murder, Enemies to Friends to Lovers, Female Frisk (Undertale), Friends With Benefits, Human, Love/Hate, Mages, Marking, Monsters, Panic Attacks, Soulmate-Identifying Marks, Underfell Alphys (Undertale), Underfell Asgore Dreemurr, Underfell Flowey (Undertale), Underfell Frisk (Undertale), Underfell Grillby (Undertale), Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underfell Undyne (Undertale), Underfell W. D. Gaster, Unrequited Love, soulmate
Language: English
Status: In-Progress
Published: 2021-02-21
Updated: 2021-02-21
Packaged: 2021-03-17 21:55:40
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,396
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29599329
Author URL: https://archiveofourown.org/users/Soulstes/pseuds/Soulstes
Summary: Rune Drake is an alpha mage, who works as a scientist, she was trying to work out a way to create a portal to another world. She succeeded in creating the portal and walks through it. Only problem now is she gets stuck in another world surrounded by monster who want to take her soul. Non of the monsters are able to even see her soul let alone steal it until she meets a monster who can access her soul. That monster happens to be her soulmate only problem is he almost killed her, she wants nothing to do with him, and both deny that the other is their soulmate. How long can they resist the pull of their souls?
Relationships: Alphys/Undyne (Undertale), Frisk (Undertale) & Everyone, Frisk/Sans (Undertale), Papyrus (Undertale)/Original Female Character(s), Sans (Undertale) & Original Character(s), W. D. Gaster & Papyrus & Sans





	Survival of the Fittest

The world is cruel. There is little kindness to be had and even those who naturally have a kind heart have learned the hard way that they must show no weakness less they be swallowed whole by the cruelty of the humans. Hiding what you truly are is no easy feet yet it is something that must be done. Humans have it hard, but mages have it worse. Imagine having magic at your finger tips, it take practice to learn how to use it properly once that is done pure power in with in ones hand, and that gift you worked so hard to cultivate into something truly wonderful can never be shared with the world.

Rune Drake found her self in that predicament every day of her life. As an alpha mage she had more power that seven beta mages combine, physically she was taller, stronger, faster, sharp senses of a true predator with the instincts to mach. Rune constantly had to fight her strong instincts, the need to put weak humans in their place, the need to keep every other mage she encountered in check, the need to hunt, the need to find and claim a mate. Worst of all do to the amount of magic Rune possessed her body forced itself to under go a painful heat that lasted two weeks every six months. On the bright side by being a mage she only had to suffer through four periods a year one every three months. Still it sucked. To combat her nature Rune dove into the research of everything having to do with magic, biology, science, mathematics, and theoretical physics. After several years of study Rune finally developed a potion that would prevent her from going into heat. Farther more to ignore the instincts her soul screamed out at her Rune preformed a ritual sealing her soul inside her chest by rune tattoos covering the skin over her ribcage that made it an actual cage, a lock tattoo rested directly on over her sternum to complete the lock. Rune was the only one who could access her soul by creating a magic key that would unlock her rune cage and allow her soul to be drown out the only other being who could ever bring out her soul was her true soulmate, but Rune was 100% positive she did not have a soulmate so her soul was perfectly safe.

After locking away her soul Rune was able to go to collage, get several PHDs, and get a job at Ebbot labs as head scientist. Of course no one knew she was a mage as then Rune herself would have been turned into a test subject. She avoided this at all costs. On the side Rune conducted research into alternate universes. The idea of other world fascinated her tell her mild interest turned into a burning obsession to prove herself right that she pushed everyone close to her away. By her late twenties after a decade of research attempt after attempt ending in miserable failure She finally figure out the secret. Everything a an equivalent numerical code by using her rune magic Rune could access that code and manipulate it to how ever she liked. She created a command screen and keyboard as a quicker access to the code, she wrote up a very complicated spell that after it was cast she would be able to use it when ever she liked, a portal would form and it would be self sustaining only requiring the initial magic to create it, as long s she knew the code or the name of the destination or could see it she could go any where in the multiverse or else the portal created would open up to a random code that would be very difficult to figure out where one was.

Rune decided to use her new portal ability to go to a new world. She made all the necessary preparations and made sure she did this on the week end so she would had plenty of time to go and get back to her world without anyone missing her. Saturday finally came around Rune left her job stopped by her home, changed into something more suitable for exploration, grabbed her back pack and off she went. Rune traveled to many worlds that weekend and saw many wonders. Every weekend for a five months she used her free time to spend time in other worlds. One Sunday she had a bad fight with her two younger sisters who where concerned with how much time Rune was spending out of their world. The argument got very heated, Rune said many things that night she would come to regret, and in a fit of blind rage Rune created a portal without thing of a code she new. She stormed off into the snowy woodlands with no supplies and only the clothing on her back.

"Rune! Rune Wait!"

"Rune come back here!"

"Shut up!"

With out thinking Rune closed the portal that would lead her home. Turning she stormed off in a random direction letting the cold air cool off her temper. With her emotions so raw her magic crackled in the air around her. Knowing exactly what to do Rune roared into the night sky unleashing a powerful wave of magic. After yelling out her frustration Rune felt a lot better. With her clear logical brain back in control it downed on Rune the horrible mistake she just made.

"Oh shit..."

Rune tried to remember the code to her own universe, but her mind drew a blank. She remember a few codes, but those where to places in her own world. When ever she explored the alternate worlds she always made sure to leave the portal back home open. It occurred to Rune that she never actually bothered to look up the code for her own world meaning she had not way to get back to her home AU. Swearing up a storm Rune opened up her window and began typing furiously on the keys trying to figure out where the hell she was and how to get back home. With her mind soul focused on the window her other normally sharp senses where dulled. Rune did not hear the crunch of snow, did not smell the sent of mustered and smoke, and she did not notice the figure behind her tell a deep male voice shattered her concentration.

"H U M A N- WHAT THE FUCK!!!"

Rune did not let the male finish speaking in the blink of an eye she close the window, turned around, and shot violet lightning from her fingertips. The male's hoodie fell off his head reviling himself to be a short big bones skeleton as she barley dodged her lightning bolts. Rune did not stick around long enough to bother taking any more details of the skeleton monster before she spun on her heel and booked in the opposite direction. With her being over six feet tall, long legs, and being in relatively good shape the snow did not slow Rune down to much as she ran. Her instincts where screaming at her that she was in danger putting her on edge as she tried to push her instincts aside to thing logically.

"are you fucking kidding me? shes a mage? Shit! SHIT!! S H I T !!!"

The skeleton had to stop the mage before she got to the town. Who knew what a fully grown alpha mage would be capable of. Only after she use magic to attack him did the skeleton realize she was an alpha. Her rank would be a big problem it she stepped into his family's territory. Not knowing what else to do the skeleton took a short cut and appeared right in from of the sprinting mage. Rune was not expecting the skeleton to appear out of nowhere unable to stop her momentum she crashed right into the skeleton. Rune fell face first into the snow hard landing on top of the skeleton. Not wanting to risk getting captured Rune opened a portal underneath them. Both mage monster where falling ten feet to the ground. the monster teleported to to ground. Rune opened a second portal right above the ground landing on her feet, dismissing the portals she took off running again.

"the hell?"

The skeleton had tried and failed to pull Rune's soul out, he saw a faint glow of violet shine through her shirt on her chest, he was not able to stop her with magic nor pull her into an encounter. With not other real options the skeleton started launching bone attack at the mage to try to slow her down or kill her. Rune waved a hand a rune circle swirled around her hand briefly then a violet magic shield appeared around her all the bone attacks ricocheted off firing into the woods and even forced the skeleton to duck in cover to avoid getting hit by his own attack.

"A HUMAN!"

"Not another one."

A very tall skeleton was marching up the path Rune us sprinting on.

"HUMAN HALT!"

"Lower your volume jackass!"

Rune called out dismissing her shield, dropping to her knees allowing her to sled right between the skeletons legs, with a magic push she was back on her feet and sprinting once more. Tall skeleton spun around jaw slightly agape as her just watched sprint. Short skeleton saw the whole thing he was not able to hold in his snick at what he had just witnessed.

"Boss the mage is getting way."

"STUP UP SANS! AFTER HER!"

"yes boss."

Sans took a short cut to in front of the mage but off to the side as he did not want to get run over again. Boss started sprinting himself to try and catch up to her. Rune managed to cover a lot of ground before her burning lungs forced her to slow down, she crossed a few bridges, dodged every monster she came across, and was getting close to a town. Sans after his sixth short cut said fuck it and just teleported to the sign outside of Snowdin to wait for to mage to arrive. Boss had to pick up his pace in order to keep up and slowly gain on the mage as she started to slow down. Boss finally caught up to her at the Snowdin sign.

"impressive you ran all the way her mage. hate to brake it to ya but this is your last stand."

"Die in a hole monster," Rune spate just before she was tackled to the ground by Boss.

"I HAVE CAPTURED YOU MAGE! I MUST SAY YOUR STAMINA IS QUIGHT IMPRESSIVE, BUT NOT AS IMPRESSIVE AS THE TERRIBLE PAPYRUS!"

Rune gasped for breath after getting the wind literally knocked out of her. Her violet eyes glared up at the skeleton who just broke her only pare of glasses. Magic started to crackle in the air surrounding her. Papyrus felt her magic, realized she was an alpha like himself, and was suddenly hit with the feeling of danger a second to late. Using almost all of her strength Rune managed to flip Papyrus she she was on top pinning him to the ground instead. Then the light show began as Rune allowed her magic to fully release her natural element of lighting. Rune electrocuted Papyrus.

" **NEHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA!!!** "

Papyrus scream echoed through our the entire cavern. Rune did not kill him, but in that moment he really wished he was dead.

"Boss!"

Sans shouted and set attacks at Rune almost instantly. Rune had not choice but to let go of Papyrus to dodge the bone attack. Every single citizen in Snowdin had heard the scream and everyone as a group went to investigate. All the sentries as far back as the ruin door had heard their captain's yell of agony they all broke into runs to aid their captain. The echo's of that scream where heard through out waterfall and even a faint murmur all the way in Hotland. A lot of Monsters wondered who made that sound and what could have caused it.

"you filthy mage!"

Sans summoned six of his blasters and shot at Rune. With no way to get out of the way in time Rune opened seven portals at once six took in each blaster blast the seventh was where all the lasers exited together increasing their strength into one powerful shot aimed directly at Sans. Sans teleported out of the way just in time, sweat drops dripped down his skull as his red eyelights turned to the mage who almost killed him. The monsters of Snowdin backed away from the mage who now had an ora of magic surrounding her. Runes's long black hair floated behind, her violet eyes where solid glowing orbs of violet power, her tattered trench coat billowed around her and her soggy pants and shirt started to steam. glowing runes appeared around Rune as she started chanting a spell circle formed around her as the spell built in power and magic cost.

"By the light that sparks in the dark of night, my enemy will not hinder my Fortune as the blood from-"

A sickening crack was heard as Papyrus swung a bone right at Rune's head. the blunt end of the bone connected with the right side of her face instantly slitting the flesh and cracking her skull. Rune's unconscious body flew several feet backwards landing in the white snow in a motionless heap blood spilled from her head wound staining the snow crimson. 

"Sans take the mage soul," Papyrus's voice was soft and horse from his blood chilling scream.

"boss i can't take her soul. there is some kind of barrier keeping it sealed inside chest," Sans explained.

Very slowly Papyrus charged bones turned to face his brother. With his entire body burnt black the look on Papyrus face was unreadable as he approached the soon to be corpse of a mage. Papyrus attempted to pull the mage soul out the runes on her ribcage glowed a vibrant violet a matching colored key made of magic formed in Papyrus's hand he unlocked the cage and her shattering soul exited the cage. It was in that moment Papyrus knew with out a shadow of a drought the mage was his soulmate... 

..............................

........

.....

...

"SHIT!"


End file.
